PATERINID^. 361 



furrow just in front of the beak, which is shown on the specimens before me and on otlier 

 species as mentioned in the discussion of the genus Micromiira (p. 335). At first sight it is 

 very difhcult to determine wliether there is an apical foramen or not, but with a strong light 

 and a high power the furrow in M. (/.) ornatella is seen to be smooth at the bottom and to 

 show no trace of an opening down through the shell. 



The surface ornamentation is of the same type as that of Af. (/.) pannvla (Wliite). It 

 differs in details, but the range of variation in the surface of M. (/.) fannula (White) is greater 

 than the differences between its surface and that of M. (I.) ornatella. 



The most marked distinction between tlie two species is in the foi-ni of the false area and 

 pseudodeltidium of the ventral valve; the dorsal valve of M. (/.) pannula also appears to be 

 more elevated. These differences, however, might disappear if we had a large number of 

 specimens of M. (/.) ornatella for comparison. With the material we now have they appear 

 to be of specific value. 



One specimen from Andrarum shows a narrow area on each side of the wide, low, triangular 

 opening, the pseudodeltidium being broken away. Shell substance corneous. 



Formation and locality. — Middle Cambrian: (8w) Limestones of the Paradoxides forchhammeri zone, at An- 

 drarum, 20 miles (32.2 km.) northwest of Simrishamn, Province of Christianstad; (320f) limestone at Andrarum, 20 miles 

 (32.2 km.) northwest of Simrishamn, Province of Christianstad ; (320n) liniestones of the Paradoxides forchhammeri zone at 

 Lovened, Djupadal, 19 miles {30.6 km.) south-southeast ofSkara, Province of Skaraborg; and (320y) limestones of the Para- 

 doxides forchhammeri zone at Gudhem, 12.5 miles (20.1 km.) south-southeast of Skara, Province of Skaraborg; all in 

 Sweden. 



(324c) Shales of Etage Id [Brogger] at Krekling, in Sandsvar, Norway. 



(161i) Limestones of the Paradoxides forchhammeri zone at Borregaard, Bornholm Island, Denmark. 



(6g) Limestone near the base of the Middle Cambrian, the lowest horizon carrying Paradoxides, northwest side of 

 Chappie Arm Harbor, about 1 mile (1.6 km.) from its head. Trinity Bay, Newfoundland. 



MicROMiTRA (Iphidella) pannula (White). 



l/ 



Text figure 32, page 362; Plate IV, figures 1, la-t, 3, 3a. 



Trematis pannulus White, 1874, U. S. Geog. Surveys W. 100th Mer., Prelim. Kept., p. 6. (Described as a new species.) 



Trematis pannulus White, 1877, idem, Final Rept., vol. 4, pt. 1, pp. 36-37, PI. I, figs. 4a and 4b. (Described and 

 discussed. The specimen represented by figs. 4a and 4b is redrawn in this monograph, PI. IV, fig. Ig.) 



Kutorgina pannula (White), Walcott, 1886, Bull. U. S. Geol. Survey No. 30, p. 105, PL VII, figs. 3, 3a; PI. VIII, figs. 

 2, 2a-c. (Copies the description and discussion given by White, 1877, pp. 36-37. PI. VII, figs. 3 and 3a, are 

 drawn from the specimen figured by White, 1877, PL I, figs. 4a and 4b. The three specimens represented by 

 figs. 3 and 3a, 2 and 2a, and 2b and 2c are redrawn in this monograph, PL IV, figs. Ig, Ij, and Ik and Ip, 

 respectively.) 



Kutorgina pannula (White), Walcott, 1887, Am. Jour. Sci., 3d ser., vol. 34, p. 190, PL I, figs. 14, 14a-b. (Character- 

 ized from a new locality. The two specimens represented by figs. 14 and 14a and fig. 14b are redrawn in 

 this monograph, PL IV, figs. Im and Iq and figs. Ik and Ip, respectively.) 



Kutorgina pannula (White), Walcott, 1891, Tenth Ann. Rept. U. S. Geol. Survey, p. 609, PL LXIX, figs. 5, 5a-f. 

 (Mentioned. Figs. 5, 5a, and 5b are copied from Walcott, 1886b, PL VIII, figs. 2a, 2, and 2b; figs. 5c, 5e, and 5f 

 from Walcott, 1887, PL I, figs. 14, 14b, and 14a; and fig. 5d from Walcott, 1886b, PL VII, fig. 3. The six specimens 

 represented by figs. 5 and 5a and 5b-f are redrawn in this monograph, PL IV, figs. Ij, Ik, Im, Ig, Ip, and Iq, 

 respectively.) 



Iphidea pannulus (White), Schucheet, 1897, Bull. U. S. Geol. Survey No. 87, p. 234. (Merely changes generic ref- 

 erence.) 



Iphidea pannula (White), Matthew, 1902, Trans. Roy. Soc. Canada for 1902, 2d ser., vol. 8, sec. 4, No. 3, p. 110. (Char- 

 acterized from a new locality.) 



Iphidella pannula (White), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 307. (Merely changes generic reference.) 



Kutorgina pannula {White), Pack, 1906, Jour. Geol., vol. 14, No. 4, p. 296, PL II, tigs. 1, la-c. (Discussed. Figs. 

 lb and Ic are outline drawings after Walcott's figures, 1886b, PL VIII, figs. 2a and 2b; fig. la is an outline draw- 

 ing after Walcott's figure, 1891a, PL LXIX, fig. 5d.) 



Iphidea pannulus (^^Tiite), Graeau and Shimer, 1907, North American Index Fossils, vol. 1, p. 201. (Described.) 



Micromitra (Iphidella) pannula (White), Walcott, 1908, Canadian Alpine Journal, vol. 1, No. 2, p. 244, PL I, figs. 

 1, la-c. (No text reference. Figs. 1, la-c are copied in this monograph, PL 'IV, figs. Ir, le, Id, and Iq, respec- 

 tively.) 

 Ventral valve conical; beak slightly incurving over the pseudodeltidium. Cardinal slopes 



rounded and flattened so as to form a not very strongly defined false area on each side of the 



wide, triangular opening, wliich is crossed toward the summit by a low, highly rounded pseudo- 



